The Atlantic Monthly was hosting the dinner in part to showcase the intellectual and literary firepower of its contributors. The magazine had invited 58 distinguished writers. Holmes and Longfellow were there, as was the great philosopher Ralph Waldo Emerson, then 74 years old. The Boston Daily Advertiser called the assemblage "without doubt the most notable that has ever been seen in this country within four walls."

Twain, who at 42 was much younger than the august group gathered before him, thought he’d have some good-natured fun at their expense. He launched into a story about a lonely old miner in southern California who’d been visited by three disreputable tramps: Mr. Emerson, Mr. Longfellow and Mr. Holmes. The miner described Emerson as ‘a seedly little bit of a chap, red-headed,’ while Holmes was ‘as fat as a balloon’ and Longfellow was ‘built like a prizefighter.’

Twain recounted how the poets quoted apposite selections from their poetry at the miner, while drinking his whiskey and playing cards. “They swelled around the cabin and spouted,” said Twain. Then they fought, made the miner sing “When Johnny Comes Marching Home.” In the end, he reveals the three tramps are imposters.

As Twain later told the story, there were 50 or 100 people at the banquet:

“Mr. Emerson, supernaturally grave, unsmiling; Mr. Whittier, grave, lovely, his beautiful spirit shining out of his face; Mr. Longfellow, with his silken white hair and his benignant face; Dr. Oliver Wendell Holmes, flashing smiles and affection and all good-fellowship everywhere like a rose-diamond whose facets are being turned toward the light first one way and then another—a charming man, and always fascinating, whether he was talking or whether he was sitting still (what he would call still, but what would be more or less motion to other people.”

They listened with attentive interest, he wrote. After the first 200 words, Twain began to expect laughter, but heard none.

“Now, then, the house's attention continued, but the expression of interest in the faces turned to a sort of black frost. I wondered what the trouble was. I didn't know. I went on, but with difficulty.” In the end, he said, he didn’t know enough to just give up and sit down.

His friend William Dean Howells was also at the dinner. Howells described the speech as “the amazing mistake, the bewildering blunder, the cruel catastrophe.”

“After the first two or three hundred words,” wrote Howell, “those Atlantic diners became petrified with amazement and horror. Too late, then, the speaker realized his mistake. He could not stop, he must go on to the ghastly end.”

Several days later, newspapers across the country reported on the speech, many proclaiming it ‘in bad taste.’ The San Francisco Daily Evening Bulletin claimed sales of Twain’s books had dropped off, and it was even suggested he moved up his planned departure for Europe to avoid the negative publicity.

Twain wrote in his autobiography that he tried to forget about the dinner for years. In 1906, an acquaintance he called “Mrs. H.” wrote to him about it, saying her family found humor in his story about the miner.

Twain dug the speech out of his files, and found it didn’t have a single defect. “It is just as good as good can be. It is smart; it is saturated with humor. There isn't a suggestion of coarseness or vulgarity in it anywhere.”

Several days later, he looked at it again and called it ‘offensive and detestable.’ And then he reversed his opinion again.

Whatever it was, the speech was memorable. It is still, to this day, being discussed by scholars and historians.